(Medical Xpress)—Remember as a child turning sticks into make-believe airplanes that soared and buzzed like bumblebees through the backyard? Or, did you play for hours with an imaginary friend in your own special world?

Researchers have found that those early pretend memories can resurface to inspire in adulthood, according Case Western Reserve University psychologist Sandra Russ.

In her new book, Pretend Play in Childhood: Foundation of Adult Creativity (American Psychological Association, 2014), Russ explores how unstructured, free play in builds a foundation for adult creativity that can lead to scientific discoveries, new engineering designs, architectural wonders, best-selling novels, paintings and other art forms.

The book provides an overview of many studies Russ and others have conducted that examine the role of play and creativity in the lives of children and adults. She also provides case studies of scientists and artists, who have reported how their childhood play experiences and memories inspired their creativity.

Examples of this childhood creativity spilling into adulthood are artists Frida Kahlo and Alexander Calder. Kahlo had an imaginary childhood friend who kept the bedridden child company, and later that imagination came to life in her surrealist paintings. Likewise Calder's love for making his own moving toys, evolved into an entertaining circus during his 20s and eventually his famous mobiles.

Similar examples are in science and technology. Miyamoto, the creator of the videogame Super Mario, recalls the joys of exploration of dark caves and play. Nobel Prize winner Barbara McClintock remembers the euphoria of floating-like walks on the beach as a child and later describing as similar experience of joy in problem solving genetic problems in science.

Russ draws a link between how children experiment, build memories and express emotions through make-believe to similar processes adults use to make new discoveries or art.

"Children learn how to process emotions and develop the cognitive processes that help them experiment with the lifelong skill of problem-solving," Russ said.

Russ originally focused on creativity in adults, but began to realize from their stories that much of their creativity had roots in early childhood.

So, for more than 20 years, Russ has refocused her research on better understanding the process of how children play. She developed a test, called the "Affect in Play Scale," to measure how often children express emotions and imagination in stories they create and act-out with simple and neutral objects (like blocks and puppets).

Several abilities for creativity emerged from her research:

• Imagination to generate stories.
• Divergent thinking in using or imagining an object as something different.
• Use of a wide range of emotions within the pretend play.
• Incorporation of memories in stories.
• Flexibility to switch from one pretend situation and emotion to another.
• Self-initiation to imagine or create with little prompting.
• Discovery of joy and passion in creating that drives the child to do it time and again.

Scholars found that when adults were questioned about how they made discoveries or art, many reported in interviews similar abilities.

Russ also devotes a chapter to the role of play in evolution and how it extends to humans. For example, young animals also play and practice skills they will use to survive as .

Russ advises parents with young children to carve out free time for them to explore problem-solving and express emotions through pretend play.

She encourages parents to bring out the pots and pans, cardboard boxes and other things found around the house to let their run wild with imaginary adventures.

"Play teaches them some lifelong skills that they can take into adulthood and use in creative ways," she said.